1. Field
Embodiments of the present invention generally relate to a method and apparatus for plasma processing of a substrate and, more specifically, to a method and apparatus for etching a substrate.
2. Description of the Related Art
A plasma generated within a plasma generation source may come into contact with internal surfaces that generate particulates which can contaminate thin layers of a semiconductor structure. One approach to eliminate particulates is to line the internal surfaces with dielectric material conduits, for example quartz liners, which are relatively free of particulate-generation surfaces. Conventionally, the liners are replaced periodically and replacing the liners typically requires gaps between abutting sections or missing sections to permit insertion and removal of the liners.
FIGS. 1A and 1B are a sectional view and a close-up sectional view, respectively, of an exemplary plasma generation system 10 employing a replaceable quartz liner 12 as is known in the art. The plasma generation system 10 may be, for example, a Rapid-O Remote Plasma Source used on a chamber as depicted later in FIG. 8. The quartz liner 12 may be disposed within an enclosure assembly 14 comprising an enclosure body 16 having at least one internal enclosure surface 18 forming an enclosure passageway 20. The enclosure passageway 20 includes an input passageway 22 to receive at least one precursor gas 24 and an output passageway 26 to discharge a plasma 28 created from the precursor gas 24. The plasma 28 may be created from the precursor gas 24 in energizing passageway segments 30A, 30B of the enclosure passageway 20. The energizing passageway segments 30A, 30B are proximate to energy sources 32A, 32B, respectively, which add energy to the precursor gas 24 within the energizing passageway segments 30A, 30B and create the plasma 28.
The enclosure passageway 20 includes other segments. The precursor gas 24 travels via an input passageway segment 34 of the enclosure passageway 20 from the input passageway 22 to the energizing passageway segments 30A, 30B where the plasma 28 is created. The plasma 28 created in the energizing passageway segments 30A, 30B is delivered to the output passageway 26 via an output passageway segment 36. In this manner, the energizing passageway segments 30A, 30B of the enclosure passageway 20 may operate continuously to supply the plasma 28 through the output passageway 26.
Particulates can be generated by the plasma 28 contacting the internal enclosure surface 18 of the enclosure body 16. In order to minimize particulate generation, the quartz liner 12 is placed within the enclosure passageway 20 to guide the plasma 28 away from portions of the internal enclosure surface 18 at the energizing passageway segments 30A, 30B and the output passageway segment 36. The internal enclosure surface 18 at the input passageway segment 34 is free of the quartz liner 12 because removal of a liner segment would require small gaps between liners and erosion of the internal enclosure surface 18 would be accelerated at the small gaps.
In order to better protect the energizing passageway segments 30A, 30B and the output passageway segment 36, the quartz liner 12 may be formed as an integral body comprising energizer liner segments 38A, 38B connected to a cross segment 40 for easy installation into the enclosure body 16. The energizer liner segments 38A, 38B may slide into the energizer passageway segments 30A, 30B and interface with positioner sleeves 42A, 42B of the enclosure body 16 which position the quartz liner 12 within the enclosure passageway 20. The energizer passageway segments 30A, 30B of the quartz liner 12 are positioned to only conventionally extend from the output passageway segment 36 to distal ends 44A, 44B almost reaching the input passageway segment 34. The distal ends 44A, 44B may include angled surfaces 46A, 46B to better guide the at least one precursor gas 24 into the energizer passageway segments 30A, 30B from the input passageway segment 34. In this manner, the quartz liner 12 may be installed and removed from the enclosure passageway 20 to provide easy maintenance by allowing efficient installation and de-installation of the quartz liner 12, and provides a continuous supply of plasma 28.
However, despite the absence of a small gap between segments of the quartz liner 12, the plasma 28 has been discovered in some cases to attack selected portions 48A, 48B of the internal enclosure surface 18 near or near the positioner sleeves 42A, 42B to cause particulates 50 (FIG. 1B). The particulates 50 may fall into the energizer liner segments 38A, 38B where they may then further travel to the output passageway 26 and cause defect-causing contamination downstream of the output passageway 26. FIG. 1C is a top perspective view of the portion 48B of the positioner sleeve 42B and FIG. 2 is an exemplary particulate 50 having a width of two-hundred (200) nanometers which may be generated therefrom. What is needed is a better approach to protect the internal enclosure surface 18 from the plasma 28. The apparatus and/or method should provide ease of maintenance and reduces the probability of the particulates 50 from being generated. The apparatus and/or method should also reduce the probability that any of the particulates 50 generated depart with the plasma from the plasma generation system 10.
One approach is to protect the input passageway segment 34, the energizer passageway segments 30A, 30B, and the output passageway segment 36 with one integral non-removable liner. In this manner, owners of the plasma generation system 10 would need to replace the plasma generation system 10 when the one integral non-removable liner is no longer serviceable. This approach is prohibitively expensive in most cases. Hence, what is also needed is an affordable approach to allow maintenance and associated disassembly of the plasma generation system 10.